In most naturally occurring situations, success depends on both skill and chance. We contrast
experimental market entry decisions where payoffs depend on skill as opposed to
combinations of skill and chance. Our data show differential attitudes toward chance by those
whose self-assessed skills are low and high. Making chance more important induces greater
optimism for the former who start taking more risk, while the latter maintain a belief that high
levels of skill are sufficient to overcome the vagaries of chance. Finally, although we
observed excess entry (i.e., too many participants entered markets), this could not be
attributed to overconfidence.